David Heinemeier Hansson (of Ruby on Rails and Basecamp fame) once wrote a blog post with related advice on per-seat pricing (for a SaaS) and how this leads to chasing the biggest companies. One you've gained a very large company as a client, that company's outsize influence will affect features, fixes and direction in your product (in a negative way according to Hansson).

The Basecamp pricing model (flat monthly fee) is not often emulated by other startups, but it's worked well for Basecamp.

Why we never sold Basecamp by the seat ( (2017): https://m.signalvnoise.com/why-we-never-sold-basecamp-by-the...